东海原甲藻在不同氮源下脲酶活性及生长率对镍离子浓度的响应

Effects of Nickel Ion Concentration on Urease Activity and Growth Rate of Prorocentrum donghaiense in Different Nitrogen Sources

以尿素、硝酸盐和铵盐为氮源时，研究微量的自由态镍离子（Ni’）浓度变化对中国近海典型赤潮甲藻一东海原甲藻（Prorocentrum donghaiense）脲酶活性及其生长率影响。结果表明：未络合的微量Ni’的浓度不会影响东海原甲藻在硝态氮和铵态氮为氮源下脲酶活性和生长率，但低自由态镍离子的浓度（[Ni’]〈1pmol／L）显著影响其在尿素氮源下的脲酶活性和生长率。Ni’的浓度在3pmol／L～1nmol／L之间，东海原甲藻的脲酶活·眭和生长速率稳定在（8．46±1．12）fmol／（h·cel）和（2．15±0．12）／d。尿素氮源下，脲酶活性与生长率成显著的正相关（P〈0．01，n=27）。同时尿素氮源也促进了东海原甲藻对镍的吸收。相同其它条件下，东海原甲藻在尿素氮源下胞内镍含量均高于硝态氮和铵态氮。

Using urea, nitrate and ammonium as nitrogen sources, the effects of unchelated Ni by EDTA on growth rate and urease activity of Prorocentrum donghaiense were studied in laboratory. As expected, there were no influence on urease activity and growth rate of P, donghaiense when growing on nitrate and ammonium for different concentration of unchelated Ni. Howerver, urease activity and growth rate of P. donghaiense varied obviously when growing on urea for various low unchelated Ni concentrations （[Ni＇] 〈 1 pmol/L）. The growth rate and urease activity would keep at （8.46± 1.12） fmol/hr per cell and （2.15±0.12） per day, respectively, when unchelated Ni ion concentrations varied from 3 pmol/L to 1 nmol/L. Meanwhile, growth rate and urease activity presented significantly positive correlation （p 〈 0.01, n = 27）. It appeared that Ni uptake was affected by nitrogen sources, and the content of Ni in P. donghaiense would be higher when growing on urea than that when growing on nitrate and ammonium.